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How Would You Use This Cooling Fan?

Also: Art Reis wasn’t the only one to weigh in about considerations when using LED lamps

Fig. 1: Use an old muffin fan to keep fumes from your face when soldering. Steve Tuzeneu, CBT, is a network staff engineer for the Bible Broadcasting Network in Charlotte, N.C., Steve periodically submits tips that readers find helpful, and the one shown here is no different.

When soldering, Steve uses an old cooling fan to keep fumes from your face; see Fig. 1.

An old 115 VAC cooling fan isn’t a bad accessory for your tool box, especially if you are a contract engineer. I’ve seen them hung to keep an exciter on the air until the proper replacement fan can be ordered, or used for cooling satellite receivers mounted in hot, non-air conditioned rack rooms.

You probably have a few favorite uses. Email them to me with a high-resolution picture to share with other Workbench readers. The address is [email protected].


Engineer Randy Wells handles engineering for a number of stations based in Santa Rosa, Calif. He writes to tell us he enjoyed reading the detective work about Art Reis and his flashing LED lamps (April 27 Workbench).

Randy points out, though, that if one of the incandescent bulbs remains in the circuit, it will act like a shunt across the remaining LED bulbs, and the LED versions will not flash.


Randy wasn’t the only one to notice the flickering LED problem. Hank Landsberg, principal of Henry Engineering and Sine Control Technology, experienced similar flickering and flashing LED “on-the-air” tally lights connected to Henry Engineering’s Superelay.

When the Superelay turns OFF, the LED tally light will sometimes flicker. This is because the 115 VAC solid-state relay that powers the light has a miniscule amount of leakage current even when it’s off, and this causes the LED light to flicker.

To solve this problem, the new Superelay II, introduced at the NAB Show, has a dedicated “LED” DC output that’s controlled by a transistor (not the 115 VAC solid-state relay), so the LED will turn off completely when it’s supposed to. Another advantage of this approach is that the Superelay II also provides 12 VDC to power the LED light directly, eliminating the need for a separate power supply or “wall wart” transformer.

Henry Engineering is celebrating its 34th anniversary this year. Seems like only yesterday I was building studios in 1982 and wiring up a Superelay to the on-air lights. Congratulations, Hank!


Donald Chester, who does AF/RF consulting from Woodlawn Tenn., also commented about Art’s experience with LED bulbs and light switches.

First, those old ceramic push-button light switches are highly desired by preservationists. Donald has seen them go for $30 to $40 apiece on eBay. Donald writes that the replacement push-button switches manufactured today and available at the big box store are off-shore replicas, cheaply made. The originals, with ceramic bodies and heavy contacts — if not abused from over-current or damaged by lightning surges — are likely to work perfectly, even though they may be 100 years old or more.

In his home, Donald has a couple of LED bulbs controlled with the original push-button switches; they have operated for years with no problems, ever since LED bulbs became available. Some electricians have the idea that something about them is unsafe and routinely replace them with $2 plastic-junk toggle switches from the big box stores, but what can be unsafe about a solidly-built SPST switch isolated from ground with a heavy ceramic body? In any case, if a metal box is used to house the switch, according to code, and the box is grounded properly, it is extremely unlikely to be any conceivable safety hazard.

If you have a friend who insists on replacing them, tell him not to throw them away but to send them to Donald.


Art Reis offers a final suggestion when replacing incandescent with LED bulbs. The quality of LED bulbs varies widely, apparently. That being the case, beware of the cheaper ones for use with “lit” switches. Test each type you get and stick with LED bulbs, which will work with either dimmers or lighted switches.


Avel Ureno is owner and chief financial officer of Exell Battery. The company can provide part number Exell Battery 457, an Eveready “B” battery direct replacement for the 67.5 V battery used in the older AM field intensity meters.

Delta Electronics President Bill Fox points out that Exell also provides the battery that powers the DC amplifier in the Delta OIB-1 Operating Impedance Bridge.

For the OIB-1, the 10.5 V Duracell PC177A or Mallory TR177 is used. This battery is also available from Exell as part number A177.

Exell provides a range of batteries. Visit its website at For service information on Delta products, visit

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